In order to enhance performances or safety of lithium battery, capacitor or the like, numerous investigations has been made for utilizing gel or polymer electrolyte in place of liquid-state electrolyte that has been conventionally used. As for polymer electrolytes, investigations have been made on alkylene oxides added with electrolyte salts such as lithium perchlorate, lithium methanesulfonate, and lithium bis(trifluoro methane sulfonyl imide). Nevertheless, satisfactory ion conductivity at room temperature or at 25° C. has not been achieved yet as hampered by thermo-dynamical mobility of the alkylene oxide polymer chains. Moreover, the alkylene oxide polymers are defective in thermal stability and start to decompose at a temperature of 180° C. or more.
Meanwhile, ionic liquid that has recently attracted attentions exhibit good ion conductivity. Nevertheless, if the ionic liquid is highly viscose, the ion conductivity deteriorates. Moreover, when the ionic liquid is converted to solid state by being combined with polymer compounds, mobility of the ions is hampered by constrictions on motion of macromolecular chains; thus density of the ions and thereby the ion conductivity are further decreased. Please see JP-1998(H10)-265673A.
In view of the above, it is aimed to provide precursor compositions capable to form a solid-state electrolyte having good ion conductivity and high heat-resistance by simple curing procedure such as casting into a mould or onto a surface, as well as to provide gel electrolyte obtainable from the precursor compositions.